Assessing combined toxic effects of tetracycline and P25 titanium dioxide nanoparticles using Allium cepa bioassay

Usage of titanium dioxide nanoparticles (TiO(2)NPs) and tetracycline (TC) has increased significantly in the present era. This leads to their release and accumulation in the environment. Both the compounds, individually, can have adverse toxic effects on the plants. Their binary mixtures can increase this degree of damage. The present study aimed to evaluate the toxicity of both the contaminants in individual and binary mixtures inAllium cepa. Further, the toxicity of TiO(2)NPs upon UVA pre-irradiation was also measured. Results showed that UVA pre-irradiated NPs (UVA-TiO(2)NPs) had a significant decrease in cell viability than their non-irradiated counterparts (NI-TiO2), denoting an increase in photocatalytic activity upon UVA pre-irradiation. Very low concentrations of TC (EC10= 0.016 mu mol/L) mixed with TiO(2)NPs significantly increased the toxicity for both UVA-TiO(2)and NI-TiO(2)NPs. Intracellular ROS generation was significantly high for UVA-TiO(2)NPs. However, TC did not have any effects on ROS production. Both the compounds exhibited genotoxic potential inA. cepa.Different chromosomal abnormalities like anaphase bridges, telophase bridges, laggard chromosomes, binucleate cells, etc. were observed. The binary mixture of UVA-TiO(2)NPs and TC showed the highest chromosomal aberrations (64.0%+/- 1.26%) than the mixture with NI-TiO(2)or the individual contaminants. This decreased significantly after recovery (46.8%+/- 1.92%), denoting the self-repair processes. This study proved that UVA-TiO(2)NPs were more toxic and could be enhanced further when mixed with a sub-lethal concentration of TC. This work will help to assess the risk of both compounds in the environment. (c) Higher Education Press 2020

Automated summary

The study found that the binary mixture of titanium dioxide nanoparticles and tetracycline significantly increased cytotoxicity in plants, especially under UVA pre-irradiation. It also showed that both compounds had genotoxic potential in Allium cepa, leading to different chromosomal abnormalities.